The hypothesis was to have MPD on the surface, the MPD would diffuse is to the surface of the parent material creating an alloy. This alloy would then have a lower melting point then the parent material. If the composition of the alloy was right the alloy would both melt and flow by capillary forces to for example contact points between the pressed plates in the heat exchanger. To succeed the joints need to meet the following three criteria:
1) Substantial size and form of the materials to be joined, so that the joint can be loaded.
2) The composition of the joint should also be more similar to the parent material, therefore having mainly the properties of the parent material and not of the melting point depressants properties. The opposite is if the composition of the joint would be mainly formed by the applied material the method would instead be soldering or brazing, and therefore also mainly having the material applied properties.
3) The joint also needs to be wet onto the material to be joined with a contact angle less than 90°.
To obtain these three criteria the MPD needs to be dissolved and diffuse into the top layer of the plate without being consumed by reactions, evaporated or diffusion to rapidly into the base material so that no melt is formed. The alloy that is formed must have a viscosity that enables flowing of the melt at the joining temperature. The melt can only be formed if the amount of MPD is high enough in the parent material to create a melt at the joining temperature. The melt that is formed must have the properties to wet the material to be joined. The right amount and ration of the MPD must be applied.